The research reported in this paper attempts to explain variation in career intent among physicians at a U.S. Air Force hospital. A causal model which comes from the research of Price-Mueller and their colleagues is used to explain career intent. The model is estimated with data collected from Wilford Hall Medical Center, the U.S. Air Force's tertiary-care center. Data were collected by questionnaires and from records. The variables are assessed with widely used organizational measures which are generally valid and reliable. Data are analyzed by ordinary least squares regression analysis. Seven variables are the most important in explaining career intent: organizational commitment, job satisfaction, search behavior, opportunity, met expectations, positive affectivity, and promotional chances. The causal model that has been tested primarily for female employees in civilian hospitals was found to operate just as well among male physicians in a military hospital. Forty-one percent of the variance in career intent is explained in this study.

Eighteen fresh frozen human Achilles tendons were used to test the ultimate strength of repaired tendon "ruptures." Three methods, the Kessler, the Bunnell, and the locking loop, were used to test the initial strength of Achilles tendon repair. The Kessler and Bunnell methods are current standard clinical configurations described for Achilles tendon repair. Under uniform and standardized laboratory conditions, the specimens were loaded to failure. The locking loop suture method was substantially stronger than either of the other two standard configurations. The latter two did not differ significantly from each other. The results of this study may be clinically relevant in terms of the choice of the repair method for surgically treated Achilles tendon ruptures.

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We develop a new method to prove communication lower bounds for composed functions of the form f • g n where f is any boolean function on n inputs and g is a sufficiently "hard" two-party gadget. Our main structure theorem states that each rectangle in the communication matrix of f • g n can be simulated by a nonnegative combination of juntas. This is a new formalization for the intuition that each low-communication randomized protocol can only "query" few inputs of f as encoded by the gadget g. Consequently, we characterize the communication complexity of f • g n in all known one-sided (i.e., not closed under complement) zero-communication models by a corresponding query complexity measure of f. These models in turn capture important lower bound techniques such as corruption, smooth rectangle bound, relaxed partition bound, and extended discrepancy. As applications, we resolve several open problems from prior work: We show that SBP cc (a class characterized by corruption) is not closed under intersection. An immediate corollary is that MA cc = SBP cc. These results answer questions of Klauck (CCC 2003) and Böhler et al. (JCSS 2006). We also show that approximate nonnegative rank of partial boolean matrices does not admit efficient error reduction. This answers a question of Kol et al. (ICALP 2014) for partial matrices. In subsequent work, our structure theorem has been applied to resolve the communication complexity of the Clique vs. Independent Set problem.

We prove several results which, together with prior work, provide a nearly-complete picture of the relationships among classical communication complexity classes between P and PSPACE, short of proving lower bounds against classes for which no explicit lower bounds were already known. Our article also serves as an up-to-date survey on the state of structural communication complexity.Among our new results we show that MA ⊆ ZPP NP [1] , that is, Merlin-Arthur proof systems cannot be simulated by zero-sided error randomized protocols with one NP query. Here the class ZPP NP[1] has the property that generalizing it in the slightest ways would make it contain AM ∩ coAM, for which it is notoriously open to prove any explicit lower bounds. We also prove that US ⊆ ZPP NP[1] , where US is the class whose canonically complete problem is the variant of set-disjointness where yes-instances are uniquely intersecting. We also prove that US ⊆ coDP, where DP is the class of differences of two NP sets. Finally, we explore an intriguing open issue: are rank-1 matrices inherently more powerful than rectangles in communication complexity? We prove a new separation concerning PP that sheds light on this issue and strengthens some previously known separations.

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